Electronic band gap engineering, doping, strain profiles and confinement in crystalline semiconductors, is a research field made possible by epitaxial growth of two-dimensional heterostructure crystals. The ability to tailor and design the electronic environment has revolutionized semiconductor technology and has led to breakthroughs in many areas, such as modern transistors, photovoltaics and laser technologies. Nanostructured crystals, such as nanowires, have drawn a lot of attention recently and recent advances in the epitaxial growth of nanostructured crystals such as nanowires, have opened new possibilities of tailoring the electronic environment, which has led to a wide variety of promising device applications, especially electronic devices. However, the performance of electronic devices based on nanostructured crystals depends on the quality of the interfaces between the different materials used.